Conditional assignment of connection identifiers to help avoid communication errors

• US 8,478,275 B1
• Filed: 08/05/2010
• Issued: 07/02/2013
• Est. Priority Date: 08/05/2010
• Status: Expired due to Fees

• Current Assignee: Sprint Spectrum LP (Deutsche Telekom AG)
• Original Assignee: Sprint Spectrum LP (Deutsche Telekom AG)
• Inventors: Vargantwar, Sachin R.
• Primary Examiner(s): Nguyen, Tu X
• Application Number:
  US12/851,223
• Time in Patent Office: 1,062 Days
• Field of Search: 455/436, 455/432.1, 455/439, 455/437, 455/438, 455/435.1, 455/435.2, 455/442
• US Class Current: 455/438
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 76/11 Allocation or use of connection identifiers

Abstract

A method and system for helping to avoid communication errors, by ensuring that when a connection identifier (such as a Walsh code or MAC Index) is being assigned to a wireless access terminal for use in a wireless coverage area having a particular coverage-area identifier (such as a particular PN offset), the same connection identifier is not currently assigned to another access terminal in another nearby coverage area that has the same coverage-area identifier.

Claims

1. A method implemented by a radio access network (RAN) that radiates to define a plurality of wireless coverage areas, the method comprising:

the RAN receiving from an access terminal (AT) a connection request specifying a wireless-coverage-area identifier;

responsive to at least the request, (a) the RAN determining a wireless coverage area that has the specified wireless-coverage-area identifier and (b) the RAN (i) selecting a radio-link identifier that is available for use in the determined wireless coverage area, while (ii) ensuring that, in another wireless coverage area having the same wireless-coverage-area identifier, the same radio-link identifier is not currently assigned to another access terminal;

responsive to the request, the RAN assigning the selected radio-link identifier to the AT; and

the RAN using the assigned radio-link identifier to communicate data to the AT in the determined wireless coverage area.

2. The method of claim 1, wherein the wireless-coverage-area identifier comprises a pseudonoise (PN) offset.

3. The method of claim 2, wherein the radio-link identifier comprises a Walsh code.

4. The method of claim 2, wherein the radio-link identifier comprises a MAC Index.

5. The method of claim 1, wherein each coverage area is a cell sector.

6. The method of claim 1, wherein ensuring that, in the other wireless coverage area, the same radio-link identifier is not currently assigned to another access terminal comprises:

determining that the other wireless coverage area has the same wireless-coverage-area identifier; and

referring to identifier-assignment records to determine whether the same radio-link identifier is currently assigned in the other wireless coverage area, and thereby determining that the same radio-link identifier is not currently assigned in the other wireless coverage area.

7. The method of claim 1, wherein ensuring that, in the other wireless coverage area, the same radio-link identifier is not currently assigned to another access terminal comprises:

determining that the other wireless coverage area has the same wireless-coverage-area identifier; and

querying a node that serves the other wireless coverage area, to determine whether the same radio-link identifier is currently assigned in the other wireless coverage area, and thereby determining that the same radio-link identifier is not currently assigned in the other wireless coverage area.

8. The method of claim 1, wherein the determined coverage area has a first set of available radio-link identifiers and the other coverage area has a second set of available radio-link identifiers, and wherein selecting a radio-link identifier that is available for use in the determined wireless coverage area, while ensuring that, in the other wireless coverage area, the same radio-link identifier is not currently assigned to another access terminal comprises:

selecting the radio-link identifier from an intersection of the first set and the second set.

9. The method of claim 1, further comprising placing a hold on the radio-link identifier in the other coverage area, to at least temporarily prevent assignment of the radio-link identifier in the other coverage area.

10. The method of claim 1, further comprising:

the RAN determining that the wireless-coverage-area identifier is not in a neighbor list associated with the request; and

the RAN carrying out functions (a) and (b) further in response to determining that the wireless-coverage-area identifier is not in the neighbor list.

11. The method of claim 1,

wherein the request is a channel-assignment-into-soft-handoff (CASHO) request,

wherein receiving the request comprises receiving the request in a particular wireless coverage area of the RAN, the particular wireless coverage area having a neighbor list, and

wherein the coverage-area identifier is not listed in the neighbor list of the particular wireless coverage area.

12. The method of claim 11, further comprising:

the RAN determining that the wireless-coverage-area identifier is not listed in the neighbor list of the particular wireless coverage area; and

the RAN carrying out functions (a) and (b) further in response to determining that the wireless-coverage-area identifier is not listed in the neighbor list of the particular wireless coverage area.

13. A radio access network (RAN) comprising a plurality of base transceiver stations radiating to define a plurality of wireless coverage areas for serving access terminals, each wireless coverage area having a respective coverage-area identifier,

the RAN being arranged to receive from an access terminal (AT) a connection request specifying a coverage-area identifier;

the RAN being arranged to respond to at least the request by (a) determining a wireless coverage area that has the specified coverage-area identifier and (b) selecting a radio-link identifier that is available for use in the determined wireless coverage area, while ensuring that, in another wireless coverage area having the same coverage-area identifier, the same radio-link identifier is not currently assigned to another access terminal;

the RAN further being arranged to assign the selected radio-link identifier to the AT in response to the request; and

the RAN being arranged to use the assigned radio-link identifier to communicate data to the AT in the determined wireless coverage area.

14. The RAN of claim 13, wherein the coverage-area identifier comprises a pseudonoise (PN) offset.

15. The RAN of claim 14, wherein the radio-link identifier comprises a Walsh code.

16. The RAN of claim 14, wherein the radio-link identifier comprises a MAC Index.

17. The RAN of claim 13, wherein each coverage area is a cell sector.

18. The RAN of claim 13, further comprising identifier-assignment data that indicates which radio-link identifiers are available in the other wireless coverage area,

wherein the RAN is arranged to ensure that, in the other wireless coverage area, the same radio-link identifier is not currently assigned to another access terminal by referring to the identifier-assignment data.

19. The RAN of claim 13, wherein the determined coverage area has a first set of available radio-link identifiers and the other coverage area has a second set of available radio-link identifiers, and wherein the RAN is arranged to select the radio-link identifier by selecting the radio-link identifier from an intersection of the first set and the second set.

20. The RAN of claim 13, wherein the RAN is further arranged to place a hold on the radio-link identifier in the other coverage area, to at least temporarily prevent assignment of the radio-link identifier in the other coverage area.